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Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, 158-163
Shishoo, R.; Lundell, M. Text. Res. J . May 1972, 285-291. Wink, W. A. TAPPI 1961, 44(6), 171A.
Received f o r review September 4, 1979 Accepted September 22, 1980
This paper is based on a presentation made by the author at a seminar Understanding and Assessing Fibrous Structures held on June 25-27,1979 at the Institute in Science and Technology, State University of New York,College at New Paltz, New Paltz, N.Y. 12562.
Preparation of Polymeric Buildlng Blocks from 5-Hydroxymethyl- and 5-Chloromethylf urfuraldehyde D. Chundury and H. H. Szmant' Department of Chemistry and Chemical Engineering, University of LhWotf, Detrotf, Michigan 4822 1
5-Hydroxymethyl- (1) and 5-chloromethylfurfuraldehyde (2) are relatively unstable and hence were converted to where R = -0-, (CH,),C6H2-, 2,5fifteen difunctional aldehyde systems such as R(CH~2,5-t~randiyl)CHo)~, thiiphenediyl, -S(CH&S-, ( ~ & ) 2 c ( c H ~ 2-S(l,3,4thladia~0l~2,ediyl)S-, , etC. The blsGhalcone and dicarboxylic acid derivatives of 1 were also prepared. These difunctional compounds are suitable building blocks for the preparation of polymers.
Introduction The preceding two papers of this series (Szmant and Chundury, 1981a) describe the preparation of 5-hydroxymethyl- and 5-chloromethylfurfuraldehyde(1, HMF, and 2, CMF, respectively) in high yields. In this paper we report how, in view of the relative instability of 1 and 2, these products were converted to more stable, difunctional derivatives that are potential polymeric building blocks containing aldehyde, alcohol, or carboxylic acid functions. Examples of polymeric Schiff s bases derived from the dialdehydes described here will be published elsewhere (Szmant and Chundury, 1981b). Experimental Section Most reagents and solvents were commercially available, and in the case of practical grades, they were purified before use. 2,5-Dmercapto-l-thia-3,4-diamle (VANCHEM NATD) and disodium 2,5-dimercapto-l-thia-3,4-diazole in water (40%,VANCHEM NATD) were supplied by R. T. Vanderbilt Co., Norwalk, CT. Mercaptoethyl cyclohexylmercaptan and 4,4'-isopropylidenediphenol (bisphenol-A) were supplied by the Pennwalt and Dow Chemical Corp., respectively. The solvents were distilled and stored over molecular sieves (4A). Boron trifluoride etherate was distilled at reduced pressure before use. Alcoa Alumina F-1 (80-200 mesh, slightly acidic), aluminum oxide 90 acidic (activity stage I, 70-200 mesh, Applied Science Laboratories, College Park, PA), and silica gel (60-200 mesh, J. T. Baker Chemical) were activated at 100 "C for 2 to 48 h before use in column chromatography. Aluminum oxide GA (10% CaSO, binder), aluminum oxide 150 acidic (Type T, Applied Science Labs.), and silica gel GF 254 were used for thin layer chromatography. The progress of the reactions was monitored by TLC using microplates. The plates were developed using an iodine chamber or by carefully spraying with concentrated H2S04 ( 5 % methanol) or DNPH solution and charring at 110 "C for a few minutes. Rf values of the new compounds were determined using precoated silica gel 01964321/81/1220-0158$01.00/0
plates in CH2C12/CC14/EtOAc= 75/15/10 as v/v unless stated otherwise. Aluminum oxide HA (no binder, Applied Science Labs.) and silica gel GF254 were used as dry packing materials for the preparation of MPLC (medium pressure liquid chromatography) columns supplied by Applied Science Laboratories (pressure range of 0 to 100 psi). The elemental analyses performed by MHW Laboratories, Phoenix, AZ, were satisfactory. All of the furan compounds employed and prepared in this work are listed in Table I. Preparation of 3. From Sucrose. A saturated 80111tion of sucrose (171 g, 0.5 mol) in M e a 0 (500 mL) and boron trifluoride etherate (25 mL, 0.2 mol) was subjected to a liquid-liquid continuous extraction using cyclohexane for 8 days. The separation of 1 and 3 was best achieved by means of an alumina F-l(350 g) column and a mixture of ethyl acetate and toluene (20/80 as v/v). 3 was recrystallized from hot benzene after a charcoal treatment. The yield of plate-like, colorless crystals of 3, mp 111-112 "C (lit. value 112 "C, Dunlop and Peters 1953) was 17.3%. It was observed that acidic alumina catalyzed the dehydration of 1 to 3 when a mixture of 1 and 3 was eluted during column chromatography. From Fructose. Fructose (9 g, 0.05 mol) was dissolved in a minimum amount of M e a 0 (25 mL) and the solution was added to 200 mL of toluene in a flask fitted with a Dean-Stark trap. BF3Et20 (1.90 mL, 0.016 mol) was added and the mixture was refluxed for 12 b A 60% yield (1.91 g) of 3 and 3-4937 of 1 (alumina F-1, 150 g) were isolated. The above experiment was repeated using ptoluenesulfonic acid (0.015 mol) and 3 (53%) and HMF (6-7 9%) were isolated along with unidentified material (alumina F-1). From HMF. Several experiments were carried out to prepare 3 in high yields from 1 using benzene, toluene, or xylene at reflux and acid catalysts such as boron trifluoride etherate, boron trifluoride, phosphoric acid, anhydrous phosphorus pentoxide, sulfuric acid, and p-toluenesulfonic acid. Water was removed by means of a Dean-Stark trap @ 1981 American Chemical Society
Ind. Eng. Chem. Rod. Res. Dev., Vol. 20, No. 1, 1981 159 Table I. Furfuryl Derivatives of 1and 2 no.
mp,b-d "C
furfuryl derivativesa
Rfe
yield, %
0.102
f
0.615
f
111-112c
0.301
76
209-21 0
near origin
93
122-124
0.605
95
0.473, 0.515
16
oil
0.701
41
139-141
0.398
31
9
oil
0.610
43
10
117-118
0.391
55
11
oil
0.605
8
12
oil
0.490
53
13
109-1 1 0
0.220
90
14
139-140
0.375
85
15
76-77
0.350
80
oil or semi-solidC 38-39
77-78
16
oil
0.340
65
17
142-143
0.490
55
18
200dd
0.175
99
19
9 5-9 7
0.345
95
20
97-101
0.485
80
R = -CH,( 2,5-furandiyl)CHO. Melting point is uncorrected. Lit. mp values for 1= 31.5, 2 = 37-38, 3 = 112 and Decomposed q t 200 "C. e Rf (TLC, silica gel GF254, eluted with 4 = 210 'C, respectively (Dunlop and Peters, 1953). CH,CI,/CCI,/EtOAc as 75/15/10 as v/v. f Szmant and Chundury (1980). Small amount of 2,4-isomer is present.
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and the disappearance of 1was monitored using TLC. The highest yield of 3 was obtained using the following procedure. A solution of 1 (5 g) and 200 mL of toluene were refluxed for 1 h to remove residual water using the Dean-Stark trap. p-Toluenesulfonic acid (0.1 g) was added to the solution followed by small portions of anhydrous phosphorus pentoxide added at regular intervals (total = 0.2 to 0.3 g) until the disappearance of 1 was completed in 12 h. After neutralization, extraction, and concentration,3 was isolated in 76% yield (1.9 g) from a simple silica gel column upon elution with methylene chloride. Traces of two unidentified compounds were also present. Boron trifluoride etherate in neat 1 as well as in toluene solution did not promote the formation of 3. The use of phosphoric and sulfuric acids gave 3 together with unidentified side products. The formation of 3 was more rapid in xylene but some byproducts were also produced. Preparation of Oxo-bis(8methylfuroic acid), 4. Relatively low yields (50-65%) of 4 were obtained using KMn04 in basic conditions (Dunlop and Peters, 1953; Pasto and Johnson, 1969) or chromic acid in acetone (Pasto and Johnson, 1969). Silver oxide (Iseki and Sugiura 1939) in basic conditions gave 4 in high yields using the following modified procedure. 3 (0.47 g, 0.002 mol) was added in small portions to a brown semi-solid paste of freshly prepared silver oxide (0.5 g, 0.004 mol) at 0 "C with constant stirring for 5 min (from equimolar silver nitrate (0.69 g) and sodium hydroxide, 1.6 mL as 10% solution). The complete dissolution of 3 occurred when 15-18 mL of acetone was also added. After 10 min, the mixture was filtered and the black precipitate was washed with 10 mL of hot water. The filtrate was acidified with dilute hydrochloric acid and was left overnight in the freezer. Colorless, shiny plates of 4 were isolated in 90-93% yield, mp 209-210 "C (lit. value 210 "C, Dunlop and Peters, 1953). Rf = near origin. Preparation of Chalcone 5 from 3. 3 (0.005 mol, 1.172 g) and acetophenone (0.01 mol, 1.166 mL) were allowed to react in 70% aqueous ethanol under nitrogen (Szmant and Basso, 1952) in the presence of four drops of a 10% sodium hydroxide. The disappearance of 3 was monitored with TLC. 5 precipitated as the reaction progressed over 3 days at room temperature. 5 was recrystallized from 95% ethanol containing a few drops of ethyl acetate. Slightly yellow crystals were isolated (2.2 g) in 95% yield, mp 112-4 "C. R, = 0.60-0.61. lH NMR (CDC13/Me4Si)(ppm): 4.61 (CH2,s, 4), 6.47 (H-4, d, 2, J = 3.5 Hz), 6.69 (H-3, d, 2, J = 3.5 Hz), 7.56 (aromatic-H, s, 10) and 7.96 and 8.12 (vinyl-H, dd, 4, J = 2.4 Hz). Preparation of 6 and 7 from Thiophene. From HMF. Thiophene (0.005 mol, 0.4 mL) was added to stirred 1 (0.01 mol, 1.2 g) at 0 "C under nitrogen. BF3Eb0 (1.26 mL, 0.01 mol) was added dropwise to the mixture and the disappearance of 1was monitored by TLC. After 2.5 h the reaction mixture was diluted with water, neutralized with NaHC03 and extracted with ethyl acetate. The concentrated extract was spotted (as a line) on a preparative TLC plate (silica gel GF254, 2000 p thickness) and eluted with CH2C12/CC14/EtOAc= 75/15/10 as v/v. The positions of the mono-, dialkylation product and 3 were marked on the plate by means of ultraviolet light. The products were recovered from silica gel using a Soxhlet extractor and methylene chloride. Large-scale separation utilized a silica gel column and toluene and ethyl acetate (99/1) as eluent. The dialdehyde 6 was obtained as a colorless powdery material, mp 77-78 OC, in 8-9% yield after crystallization
from toluene containing a few drops of ethyl acetate. Two isomeric forms of 6 were observed by TLC (R,= 0.473 and 0.515) but their separation was not attempted. lH NMR (CDC13/Me4Si)6 (ppm): 4.23 (CH2, s, 4), 6.28 (H-4, d, 2, J = 3.5 Hz), 6.78 (thiophene-H, s, 2), 7.17 (H-3, d, 2, J = 3.5 Hz) and 9.48 (CHO, s, 2). The 2,4DNPH derivative of 6 gave a mp at 168-171 "C. The monoalkylation product 7 was treated with charcoal and isolated (419%) as a slightly yellow colored oil. R, = 0.701. 'H NMR (CDC13/Me4Si)6 (ppm): 4.18 (CH2,s with shoulder, 2), 6.23 (H-4, d, 1, J = 3.5 Hz), 6.82 to 7.21 (H-3 and thiophene-H, m, 3) and 9.51 (CHO, s, 1). It gave a 2,4-DNPH derivative mp 146-148 "C. From CMF. Thiophene (0.4 mL, 0.005 mol) and anhydrous aluminum chloride (1.33 g, 0.01 mol) were added to 50 mL of nitromethane under nitrogen and CMF (1.45 g, 0.01 mol) in 5 mL of nitromethane was introduced. The reaction was allowed to run for 2 h at 0 "C and then 6 h at room temperature but 7 and 8 could not be detected. Anhydrous stannic chloride (1.15 mL, 0.01 mol) was then added and the stirring was continued for an additional 24 h at room temperature. After workup as described above, 7 was obtained in 15-16% yield as well as traces of 8. No formation of alkylation products was observed using anhydrous zinc chloride or boron trifluoride etherate. Preparation of 8 and 9 from g-Dimethoxybenzene. From HMF. HMF (3.87 g, 0.03 mol) and p-dimethoxybenzene (2.07 g, 0.015 mol) were added to 100 mL of distilled nitromethane (Dehaan and Covey, 1978) under nitrogen. The reaction mixture was heated at reflux with stirring and BF,Et,O (3.78 mL, 0.03 mol) was added at once followed by 1.4 g of anhydrous P205in small portions. After 2 h, the mixture was worked up as described above and the products were separated using MPLC to give 8 in 11-12% yield after recrystallization from 95% ethanol and a few drops to ethyl acetate. The colorless crystals gave mp 139-141 "C. R, = 0.39-0.41. 'H NMR (CDC13/Me4Si)6 (ppm): 3.66 (CH3,s, 6), 3.95 (CH2,s with shoulder, 4),6.08 (H-4, d, 2, J = 3.5 Hz), 6.67. (aromatic-H, s, 2), 7.08 (H-3, d, 2 J = 3.5 Hz), 9.43 (CHO, s, 2). The 2,4-DNPH derivative of 8 gave mp 185-189 "C (softened). 9 was obtained in 42-43% yield as a yellow oil that turned dark on prolonged exposure to the atmosphere. R, = 0.6M3.62. lH NMR (CDC13/Me4Si)6 (ppm): 3.68 (CH3, d, 6, J = 1.8 Hz), 3.96 (CHZ, 8, 2), 6.11 (H-4, d, 1, J = 3.5 Hz), 6.73 (aromatic-H, s with shoulder, 3), 7.08 (H-3, d, 1, J = 3.5 Hz) and 9.46 (CHO, s, 1). The 2,4-DNPH derivative of 9 gave mp 166-169 "C (softened). The separation of 8,9, 3 and 1 by means of a column packed with aluminum oxide (acidic, activity stage I, 70-200) also gave rise to unidentified side products. From CMF. Anhydrous aluminum chloride (1.33 g or 0.01 mol), stannic chloride (1.15 mL, 0.01 mol) and p-dimethoxybenzene (0.69 g, 0.005 mol) were added to 50 mL of nitromethane under nitrogen and 2 (1.45 g, 0.01 mol) in 5 mL of nitromethane was then added dropwise. The reaction was allowed to run for 2 h at 0 "C (no evolution of HC1 was observed) and then 24 h at room temperature 8 was obtained (two isomers) in 30-31% yields together with traces of 9. The above reaction was unsuccessful using ferric chloride in carbon disulfide. Preparation of 10 and 11 from m-Dimethoxybenzene. From 1. 1 (2.52 g, 0.002 mol) and distilled m-dimethoxybenzene (1.31 mL, 0.001 mol) were added to 50 mL of distilled nitromethane under nitrogen and BF3Eb0 (2.10 mL, 0.002 mol) was added a t once to the stirred solution at reflux followed by 0.9 g of anhydrous P205added in small portions. The disappearance of HMF
Ind. Eng. Chem. Prod. Res. Dev., Vol. 20, No. 1, 1981 161
was monitored by TLC. After 2 h, the mono- and dialkylation products and 3 were separated using MPLC (dry aluminum oxide HA and methylene chloride). 10 was recrystallized from 95% ethanol (36-37%) and gave mp 117-118 "C. Rf= 0.391. 'H NMR (CDC13/Me4Si)6 (ppm): 3.66 (CH3, 9, 6), 3.95 (CH2,8, 4), 6.09 (H-4, d, 2 J = 3.5 Hz), 6.66 (aromatic-H, s with shoulders, 2), 7.06 (H-3, d, 2, J = 3.5 Hz) and 9.48 (CHO, s, 1). The 2,4-DNPH derivative of 10 gave mp 196-200 "C (dec). 11 was isolated as an oil in 7-8% yield and was discolored upon exposure to the atmosphere. R = 0.60-0.61. 'H NMR (CDC13/Me4Si)6 (ppm): 3.75 (Ck3, s, 61, 3.97 (CH2, s, 2), 6.12 (H-4, d, 1,J = 3.5 Hz), 6.74 (aromatic-H, s with shoulders, 3), 7.07 (H-3, d, 1,J = 3.5 Hz) and 9.44 (CHO, s, 1). The 2,4-DNPH derivative of 11 gave mp 181-184 "C (softens). From 2. 10 was isolated in 5465% using anhydrous aluminum chloride and stannic chloride in nitromethane following the procedure mentioned in the preparation of 8. No formation of monoalkylation product 11 or of any other products was observed except for a few resinous particles. Unreacted 2 (15-18%) was also recovered. Preparation of 12 from o-Dimethoxybenzeneand 1. From 1. Attempts to prepare the dialkylation product of o-dimethoxybenzene with 1 were unsuccessful. However, the monoalkylation product 12 was isolated in 53% yield as a slightly yellow oil following the procedure used in the preparation of 8, Rf = 0.48-0.50. 'H NMR (CDC13/Me4Si)6 (ppm): 3.83 (CH3,s, 6),3.97 (CH2,s, 2), 6.14 (H-4, d, 1,J = 3.5 Hz), 6.73 (aromatic-H, s, 3), 7.11 (H-3, d, 1, J = 3.5 Hz) and 9.50 (CHO, s, 1). The 2,4DNPH derivative of 12 gave mp 192-196 "C (dec). From 2. 12 was obtained in 4547% yield using the experimental conditions described in the preparation of 8. Formation of resinous materials and of two unidentified products was also observed. General Procedure for the Alkylation of Aliphatic, Aromatic, and Heterocyclic Nucleophiles with 2. A weighed amount of nucleophile was added to dry and redistilled tetrahydrofuran (THF) in an atmosphere of dried nitrogen. Freshly cut potassium metal was added to the solution with caution (hood). The completion of the salt formation was monitored by TLC following the disappearance of the nucleophile. Excess metal was removed from the precipitated solution by adding methanol dropwise until hydrogen gas was no longer evolved. Excess methanol was then removed by reducing the volume of the solution by one-third. The salt was collected,washed with dry ethyl ether, and dried under vacuum at 110-115 "C for 24 h. In another procedure the substrate was treated with an equivalent amount of sodium or potassium hydroxide. The formation of salt was promoted by the removal of water by heating the mixture overnight on a steam bath in a nitrogen atmosphere under reduced pressure using a water aspirator. Two equivalents of crystalline 2 (or a solution of the corresponding iodide) were added to a stirred solution (Me2S0or another solvent) containing one equivalent of the salt under nitrogen. The completion of the reaction was monitored using TLC and the disappearance of 2. The sodium or potassium chloride was removed by filtration. Traces of 2 were converted to HMF with 10% sodium hydroxide. The dialkylation product was extracted with ethyl acetate (3 X 75 mL), dried over anhydrous magnesium sulfate, and filtered. Slightly colored solutions were treated with activated charcoal. Ethyl acetate was removed by means of a rotary evaporator and the residue was usually recrystallized twice from 95% ethanol. DNPH
derivatives were prepared and the new compounds were characterized by means of NMR and elemental analysis. General Procedure for the Alkylation of Aliphatic and Heterocyclic Nucleophiles with 2 in the Presence of TetrabutylammoniumFluoride. A weighed amount of substrate was dissolved at room temperature under nitrogen atmosphere. Excess tetrabutylammonium fluoride (Corey and Venkateswalu, 1972; Pless, 1973) was added to the stirred solution. A calculated amount of 2 in THF was added and the solution was heated a t 60 "C in order to complete the reaction. The disappearance of 2 was monitored by means of TLC. The mixture was concentrated to a few milliliters and the product was crystallized at 0 "C. In the case of an oil it was purified by eluting it with methylene chloride from a silica gel column. Preparation of 13. A 5-mL solution of tetrabutylammonium fluoride (1.3058 g, 0.005 mol) was introduced to 100 mL of THF. 2,5-Dimercapto-l-thia-3,4-diazole (0.3 g, 0.0025 mol) was added to the stirred solution a t room temperature. After 0.5 h, 0.723 g of 2 (0.005 mol) was added to the mixture. The solution was brought to 60 "C for 15 min and ita disappearance was followed using TLC (Rl= 0.615). The reaction was completed in another 15 min by adding additional 5 mL (0.005 mol) of tetrabutylammonium fluoride solution to the reaction mixture. 13 (90%)crystallized at 0 "C from the concentrated reaction mixture and was recrystallized from 95% ethanol. The colorless crystals turned slightly yellow on exposure to light and melted a t 109-110 "C. R = 0.21-0.23. 'H NMR (CDC13/Me4Si)S (ppm): 4.70 (Ck,, s , 4 ) , 6.58 (H-4, d, 2, J = 3.5 Hz) and 9.63 d, 2, J = 3.5 Hz), 7.21 (H-3, (CHO, 8, 2). In another experiment, the yellow powder (disodium 2,5-dimercapto-l-thia-3,4-diazole) was obtained by removing water from its aqueous 40% solution. 2 (1.3 g, 0.009 mol) and 0.877 g of disodium 2,5-dimercapto-lthia-3,4-diazole (0.0045 mol) were added to 50 mL of 95% ethanol. The complete disappearance of 2 required 2.5 h at reflux temperature or 30 h at room temperature. Excess (5 to 6 volumes) of ethyl ether was added to precipitate NaCl at 0 "C overnight. The latter was filtered and slow evaporation (hood) of the filtrate resulted in crystals of 13 in 52% yield. Crystallizationwas induced by scratching the concentrated oily solution to give 3538% yield of a second crop. The recrystallization was carried out from 95% ethanol. However, traces of 5-ethoxymethylfurfuraldehyde were still present as impurities. The above experiment was repeated using dry and distilled Me2S0 to give 85-90% in 15 min at 60 "C. Preparation of 14. 5-Iodomethylfurfural (IMF, 2.95 g or 0.0125 mol) was prepared in situ from 2 (1.8 g or 0.0125 mol) using the Finkelstein reaction (Szmant and Chundury, 1981). The dipotassium salt (1.513g, 0.00625 mol) prepared from terephthalic acid using potassium metal, was suspended in a stirred acetone solution and IMF in acetone was added dropwise (10 min) at reflux. 14 was isolated in 7580% yield and after recrystallization from 95% ethanol gave colorless, shiny plates, mp 139-140 "C. R = 0.37-0.38. 'H NMR (CDC13/Me4Si)6 (ppm): 5.42 &H2, s, 4), 6.68 (H-4, d, 2, J = 3.5 Hz), 7.22 (H-3, d, 2, J = 3.5 Hz), 8.13 (aromatic-H, s, 4) and 9.64 (CHO, s, 2). The 2,4-DNPH derivative of 14 gave mp 210-214 "C (dec). The above experiment was repeated with CMF (1.8 g, 0.0125 mol) and dipotassium salt of terephthalic acid (1.513g, 0.00625 mol) in dry and distilled M Q O (125 mL) at 60 "C for 24 h in an inert atmosphere to give 14 in 85% yield.
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Preparation of 15. The dipotassium salt of isophthalic acid (1.20 g) was treated with 1.445 g of 2 (0.01 mol) in dry, redistilled Me2S0 (125 mL). After 36 h at 60 "C, the reaction mixture gave 15 in 80% yield (1.53 g). It was recrystallized from 95% ethanol to give shiny, colorless plates of 15, mp 76-77 "C. Rf = 0.34-0.35. 'H NMR (CDC13/Me4Si)6 (ppm): 5.37 (CH2,s, 4), 6.64 (H-4, d, 2, J = 3.5 Hz), 7.23 (H-3, d, 2, J = 3.5 Hz), 7.74 (aromatic H-1, broad, "t", 1,J = 6.4 Hz), 8.36 (aroamtic H-2,4, broad "d" with shoulder, 2, J = 6.8 Hz),8.75 (aromatic H-3, broad "s" with shoulder, 1)and 9.64 (CHO, s, 2). The 2,4-DNPH derivative of 15 gave mp 200-203 "C (dec). Preparation of 16. The dipotassium salt of phthalic acid, 1.18 g, was treated with two equivalents of 2 (1.445 g, 0.01 mol) in Me2S0 for 48 h to give 16 as an oil (1.24 g, 65%). Attempts to crystallize the oil were unsuccessful. R, = 0.34. lH NMR (CDC13/Me4Si)6 (ppm): 5.36 (CH2, 3.5 9, 4), 6.63 (H-4, d, 2, J = 3.5 Hz), 7.23 (H-3, d, 2 J Hz), 7.60 (aromatic-H, m, 4) and 9.63 (CHO, s, 2). The 2,4-DNPH derivative of 16 gave mp 203-207 "C (dec). Preparation of 17. The dipotassium salt of bisphenol-A, 1.14 g, 0.005 mol, prepared in 95% yield from freshly cut potassium metal and bisphenol-A in THF under nitrogen atmosphere for 2 h was placed in dry MsSO and 2 equiv of 2 (1.445 g, 0.01 mol) was introduced under nitrogen. The reaction mixture was heated a t 60 "C for 8 h. 17, isolated in 55% (1.22 g) yield, was purified by means of a short column containing silica gel with methylene chloride as the eluent. 17 was recrystallized from 95% ethanol containing a few drops of ethyl acetate to give colorless crystals, mp 142-143 "C. R = 0.48-0.49. 'H NMR (CDC13/Me4Si)6 (ppm): 1.63 (Ck,, s, 6),5.12 (CH2, s, 4), 6.63 (H-4, d, 2, J = 3.5 Hz), 7.06 (aromatic H, dd with shoulder, 4, J = 9.5 and 7.2 Hz), 7.24 (H-3, d, J = 3.5 cps) and 9.67 (CHO, s, 2). The bis-2,4-DNPH derivative of 17 gave mp 209-214 "C (dec). Preparation of 18. 4,4'-Bis(sodium benzenesulfinate) ether (3.42 g, 0.01 mol) was dissolved in 125 mL of distilled M e a 0 at 60 "C. 2 (2.89 g, 0.02 mole) in 10 mL of M e a 0 was added and the reaction mixture was heated for 2 h to give 18 in 95% yield (4.9 g). 18 was recrystallized from 95% ethanol and a few drops of ethyl acetate to give a melting point above 200 "C with decomposition. 'H NMR (Me2SO-d6)6 (ppm): 2.55 (residual CH, in MeaO, s with shoulder), 5.15 (CH2,s, 4), 6.65 (H-4, d, 2, J = 3.5 Hz),7.28 (aromatic-H, d, 4, J = 9.6 Hz), 7.50 (H-3, d, 2, J = 3.5 Hz), 7.88 (aromatic-H, d, 4, J = 9.6 Hz) and 9.56 (CHO, s, 2). Rf = 0.1734.177. The bis-2,4-DNPH derivative of 18 gave mp 213-217 "C (dec). Preparation of 19. In the first method, 0.19 g of 1,2ethanedithiol (0.002 mol) and 4 mL of tetrabutylammonium fluoride in THF (1mL = 1mmol) were added to THF (20 mL). 2 (0.58 g, 0.004 mol) in 5 mL of THF was introduced and its disappearance was monitored by TLC every 5 min for 20 min. An additional amount of 8 mL of fluoride reagent was then added to the mixture to ensure completion of the reaction in 1h. 19 was isolated in 95% yield (0.6 g), mp 95-97 "C. R, = 0.34-0.35. lH NMR (CDC13/Me4Si)6 (ppm): 2.86 (CH2,s, 4), 3.94 (CH2, 8, 4), 6.58 (H-4, d, 2, J = 3.5 Hz), 7.34 (H-3, d, 2, J = 3.5 Hz) and 9.75 (CHO, s, 2). The bis-2,4-DNPH derivatives of 19 gave mp 201-205 "C (dec). Preparation of 20. This compound was obtained in 80% yield (0.63 g) using 0.352 g of mercaptoethyl cyclohexylmercaptan (0.002 mol), 10 mL of tetrabutylammonium fluoride (1 mL = 1 mmol), and 0.59 g of 2 (0.004 mol) in THF a t room temperature for 12 h under a nitrogen atmosphere. The disappearance of CMF was
monitored by TLC. 20 was recrystallized from 95% ethanol to give colorless crystals, mp 99-101 "C. Slightly yellow coloration of 20 was observed upon exposure to light. Rf = 0.484.49. lH NMR (CDC1,/Me4Si) 6 (ppm): 1.3 to 3.3 (saturated H, broad m, 14),4.02 (CH2,s, 4),6.51 (H-4, d, 2, J = 3.5 Hz), 7.23 (H-3, d, 2, J = 3.5 Hz) and 9.71 (CHO, s, 2). The bis-2,4-DNPH derivative of 20 gave mp 189-194 "C (dec).
Results and Discussion The ether derived from 1, oxo-bis(5-methylfurfuraldehyde), 3, is an example of a bifunctional polymeric building block (Cram, 1976). 3 was claimed (Merck and Co., 1962) to be produced from 1 in 81.5% yield although in this laboratory this method gave a yield of only about 20%. It is also formed in trace amounts as a byproduct from the dehydration of hexoses or hexose-yielding carbohydrates (Iseki, 1933; Newth, 1951; Dunlop and Peters, 1953; Turner et al., 1954) by means of various acid catalysts. In connection with our attempts to utilize 1 in the alkylation of aromatic systems we found that small amounts of acidic catalysts served to form 3 in good, but not necessarily optimal, yields of 76%. The oxidation (Codignola and Piacenza, 1948; Terai, 1951) or reduction (Bremmer and Keeys, 1947; Graves, 1937) of 3 provides the corresponding diacid or dialcohol, respectively. Also, the bischalcone (Szmant and Basso, 1952) was prepared from acetophenone. In general, alkylation products of thiophene are less readily produced than the acylation products since the former often results in polymerization (Katritzky, 1963). In our hands, the alkylation of thiophene and of m- and p-dimethoxybenzenes (DMB) proceeded better with 2 than with 1. The best results were obtained when a combination of stannic and aluminum chlorides was used in order to activate 2. The diakylation of the three dimethoxybenzenes (DMB) occurred most readily in the case of the m-isomer, while with the 0- and p-DMB isomers the reaction tends to proceed with some reluctance beyond the monoalkylation stage. This is particularly true in the case of o-DMB that did not yield the dialkylation product. The behavior of the DMB compounds fits the expected orientation of the methoxy groups and the large steric inhibition produced by the first furfuryl substituent with regard to the entry of the second furfuryl group. The structure assignment of the mono- and dialkylation products of thiophene and of the dimethoxybenzenes are based on the NMR data. The different types and numbers of protons that give rise to each peak were determined from the chemical shifts and integration data. The benzenedicarboxylic acids and bisphenol-A did resist dialkylation by 2 even a t relatively high reaction temperatures and prolonged reaction time in the presence of fluoride ion catalyst although the dithiols were easily dialkylated. This behavior is consistent with the high nucleophilicity of the thiolate ion toward 2 as compared to that of the MOL,RO-, and ArO- anions, and the latter "hard" bases we apparently rather protonated than participate in a nucleophilic attack on 2. However, the dialkylation products were obtained by means of the dipotassium salts, and the use of Me2S0 (as compared to THF or acetone) was favorable presumably because of ion-pair dissociation in this solvent. Literature Cited Bremmer, J. 0. M.; Keeys, R. K. F. J . CI". SOC. 1947, 1068. CMIgnola, F.; Placenza, M. Italian Patent 439947, 1948. Corey, D. J.; Venkateswalu, A. J. Am. Chem. Soc. 1972. 94, 6190. Cram, D. J. German Patent 2 539 324, 1976.
Ind. Eng. Chem. Prod, Res. Dev. 1981, 20, 163-166 Dehaan, F. P.; Covey, W. D. J. Am. Chem. Soc. 1978, 100, 5944-5. Duniop, A. P.; Peters, F. N. “The Furans,” Relnhold Pubikhlng Corp.: New York, 1953; pp 400, 411, 557. Qraves, (3. D. US. Patent 2077409, 1937. Iseki, T.; Suglura, T. J . Biod”. Jpn. 1939, 30, 113. Isekl, T. 2. Physlol. Chem. 1933, 216, 130. Katrkzky, A. R. A&. Hetemycl. Chem. 1963, 1 , 38. Merck Company. Inc., British Patent 887300, 1902. Newth, F. H. Adv. Carbohydr. Chem. 1951. 6 , 83. Pasto, J.; Johnson, C. R. “Organic Structure Determination”. Prentlce-Hall, Inc.: Englewocd, N.J., 1909 p 383.
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Pless, J. J. olg. Chem. 1973, 39, 2644-6. Szmant, H. H.; Chundwy. D. J . Appl. Chem. Blotechnol. 1981r, in press. Szmant, H. H.; Chund D.,1981b, manuswlpt in preparation. Szmant, H. H.; Basso? . J. J. Am. Chem. Soc. 1952, 74, 4397. Terai, T. Japanese Patent 1111, 1951. Turner, J. H.; Rebers, P. A.; Barrick, P. L.; Cotton, R. H. Anel. Chem. 1954, 28. s9s.
Received for review July I, 1980 Accepted November 6 , 1980
Tough Plastics and Reinforced Elastomers from Renewable Resource Industrial Oils. A Short Review Leslie H. Sperllng,’ John A. Manson, Shahld Qureshl, and Ana M. Fernandez Materiels Research Center, Lehbh UnIversHy, Bethlehem, Pennsylvania 180 15
Industrial oits, botanical oils, and vegetable oils all refer to the oils pressed or extracted from oll-bearing seeds. Some of these oils contain chemically reactive groups, besides double bonds, that permit new classes of tough plastics and reinforced elastomers to be made. Many of these materials are nonedible but Industrially useful. This paper reviews recent and current research on interpenetrating polymer networks and simuttaneous interpenetrating networks made from castor oil (hydroxyl group), Vernonia dl (epoxy group), and epoxldized Nnseed dl (epoxy group), combined with cross-linked polystyrene. Possible applications are discussed.
polyurethane or polyester of castor oil, both of which are soft elastomers. These polymers were combined with cross-linked polystyrene to form an interpenetrating polymer network, IPN (14-16). An IPN may be defined as a combination of two polymers in network form, at least one of which was polymerized and/or cross-linked in the immediate presence of the other. Both sequential ‘IPN synthesis (2-8) and simultaneous interpenetrating network, SIN,syntheses were undertaken (9-13). The latter, involving simultaneous but independent polymerizations via step- and chain-growth mechanisms, yielded the more practical of the two routes. Beginning in 1979, research on different oils was undertaken. Experimental oils from potential new oilseed crops, suggested by the USDA, were investigated. In pmticular, epoxy-bearingoils from Vernonia (1) as well as chemically epoxidized linseed, Crambe, Lunaria, and Lesquerella oils were used (1, 17-19). While this research is continuing at the time of writing, this paper presents an integrated review of the research done to date, including chemical properties, mechanical behavior, and potential applications.
Introduction In today’s lingo, the term “renewable resources” means sources of energy or products that can be used, grown, or replenished naturally, time after time, as opposed to mineral and petroleum products, which, once used up, are gone forever. Among the renewable resources available in the world, plant products rank very high. Examples include wood, cellulose, starch, rubber, and botanical oils. These oils are usually obtained by pressing or extracting various seeds. For industrial purposes, the oils may be classified according to the principal types of chemical reactivity. Classically, the presence of multiple double bonds has allowed for ready polymerization, providing the basis for paints, adhesives, and other industrial uses. Many of these oils are also edible. Among the large volume oils of botanical origin only castor oil contains another type of reactive site, a hydroxyl group. Oils containing hydroxyl groups or other reactive groups, as discussed below, are nonedible. However, because of their high reactivity, they offer special industrial advantages. Recently, the USDA has pointed out that new oilseed crops, originating from wild plants, bear oils containing various interesting chemical groups (1). Besides other hydroxy bearing oils, keto and epoxy fatty acids, long chain fatty acids, as well as new sources of oils bearing conjugated unsaturation are being researched (1). Lehigh’s Oils Research Program Beginning at the time of the 1974 petroleum crisis, the Polymer Laboratory at Lehigh University, in cooperation with the Universidad Industrial de Santander in Colombia, South America, undertook a study of the preparation of tough plastics and reinforced elastomers based on castor oil (2-13).The synthesis route involved making either the 0196-4321/81/1220-0163$01.00/0
Materials Castor oil is the triglyceride of ricinoleic acid (1). As 0 CH2-0-C
II
I n
OH
-(CHA7-CH
CH-O-C-(CH2)7-CH
I
K
=CH-CHz-
I
CH-(CH2)5-CH3 OH
I
=CH-CH~-CH-(CHZ)~-CH~
CH2-O-C-(CH2)7-CH=CH-CH2-CH-(CH2)5-CH3
(1)
OH
I
discussed above, the interesting reactive sites are the three 0
1981 American Chemical Society
